Police chief of Marjah district, Zamaria Zarak, said on Friday that at least 13 insurgent fighters were killed in the gunbattles that followed the checkpoint attacks.

Taliban militants have been intensifying attacks on Afghan security forces seeking to destabilize the country ahead of a key presidential election in April and the pullout of most foreign coalition forces at the end of the year.

Afghanistan's 350,000-strong police and army have taken over almost all security responsibility and have suffered hundreds of casualties per month in battles, assassinations and bombings.